The present invention relates generally to wireless communication, and more particularly to an arrangement for ultrasonic wireless communication.
Consumer markets continue to request wireless electronic devices. Examples of such devices include accessories for computers, computer peripherals, and cellular telephones to name but a few. Current wireless communication can be accomplished by radio frequency carrier, optical link, or ultrasonic link.
Optical link interconnects have the problem of limited directivity, allowing them to be used only for line-of-sight communication. RF signals overcome the directivity problem, but interference, both of the signal and by the signal, can be a problem. For this reason, RF communication is regulated by the government as far as the amount of permissible power transmitted and of interference. Ultrasonic transmission is unregulated, but can also suffer from directivity problems. Moreover, RF circuitry is complicated and bulky, requiring antennas, mixers, and the like.
The marketplace also demands that wireless communication have a privacy-mode of operation. This is difficult to achieve with RF communications due to its radiative nature and the size of the necessary components can be cumbersome. Optical links can provide privacy due to their directivity, but the connection must be line of sight. In both cases power usage is an issue in portable devices as far as extending battery life.
Accordingly, there is a need for a wireless communication system that has the benefits of having a privacy mode of operation, but is not limited to line-of-sight operation. It would also be of benefit if the communication were not regulated. It would also be an advantage to provide a wireless system that provides good signal quality without consuming a relatively large amount of power and without being too expensive.